Optical article comprising an antireflective coating with a low reflection both in the ultraviolet region and in the visible region

ABSTRACT

This invention relates to an ophthalmic lens with a low reflection both in the ultraviolet region and in the visible region, comprising a substrate provided on its rear main face with a multilayered antireflective coating (3-7 layers) comprising a stack of at least one layer with a high refractive index and at least one layer with a low refractive index, having a mean reflection factor on the rear face in the visible region R m  lower than or equal to 1.15%, a mean light reflection factor on the rear face in the visible region R v  lower than or equal to 1%, a mean reflection factor R UV  on the rear face between 280 nm and 380 nm, weighted by the function W(λ) defined in the ISO 13666:1998 standard, lower than 5%, for angles of incidence of 30° and 45°, the antireflective coating outer layer being a silica-based layer. The lens according to the invention does especially prevent the reflection of the UV radiation produced by light sources located behind the wearer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending U.S. patent applicationSer. No. 13/643,272 filed Oct. 24, 2012, which is a national phaseapplication under 35 U.S.C. §371 of International Application No.PCT/EP2011/072386 filed Dec. 9, 2011, which claims priority to FrenchApplication No. 1060394 filed Dec. 10, 2010, U.S. ProvisionalApplication No. 61/421,956 filed Dec. 10, 2010, and U.S. ProvisionalApplication No. 61/541,724 filed Sep. 30, 2011. The entire contents ofeach of the above-referenced applications is specifically incorporatedherein by reference without disclaimer.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an optical article comprising on itsrear face, and optionally on its front face, an antireflective coatingwhich strongly reduce reflection in the UVA- and UVB-radiation range,and in the visible region. The optical article may especially be anophthalmic lens, especially a tinted solar lens.

2. Description of Related Art

The solar spectrum comprises electromagnetic radiations having variouswavelengths, especially ultraviolet radiation (UV). The UV spectrum hasmany bands, especially UVA, UVB and UVC bands. Amongst those UV bandswhich do reach the earth surface, UVA band, ranging from 315 nm to 380,and UVB band, ranging from 280 nm to 315 nm, are particularly harmful tothe retina.

Traditional antireflective coatings are designed and optimized to reducereflection on the lens surface in the visible region, typically withinthe spectrum range of from 380 to 780 nm. As a rule, the reflection inthe ultraviolet region (280-380 nm) is not optimized, and is frequentlyreinforced by the traditional antireflective coating itself. The article“Anti-reflective coatings reflect ultraviolet radiation”, Citek, K.Optometry 2008, 79, 143-148 underlines this phenomenon.

The mean reflection in the UVA and UVB regions may thus attain highlevels (up to 60%) for traditional antireflective lenses. For example,as regards non-solar antireflective articles which are marketed by mostof the manufacturers over the course of these recent years, the UV meanreflection does range from 10 to 25%, for an angle of incidence of from30 to 45°. It is not problematic on the front face of the lens, sincethe major part of the UV radiation which comes from the front of thewearer and might attain the wearer's eye (normal incidence, 0 to 15°)generally get absorbed by the ophthalmic lens substrate. A betterprotection against UV radiation transmission may be obtained throughsolar ophthalmic lenses, which are studied and designed to reduce thevisible spectrum luminosity, totally absorb UVB and totally or partiallyabsorb UVA.

On the other hand, the UV radiation resulting from light sources locatedbehind the wearer may reflect on the lens rear face and reach thewearer's eye if the lens is not provided with an antireflective coatingwhich is efficient in the ultraviolet region, thus potentially affectingthe wearer's health. Such phenomenon is made stronger by the trend forfashion sunglasses with high diameters which increase the risk of strayreflections getting into the eyes.

It is admitted that the light rays that may reflect onto the lens rearface and reach the wearer's eye have a narrow incidence angle range,ranging from 30 to 45° (oblique incidence).

There is currently no standard relating to the UV radiation reflectionfrom the rear face.

There are a number of patents dealing with methods for makingantireflective coatings that would be efficient in the ultravioletregion, would transmit and/or absorb the UV radiation rather thanreflect it. However, optimizing the antireflective performances over thewhole ultraviolet region reveals generally detrimental to theantireflective performances in the visible region. Conversely,optimizing only the antireflective performances in the visible regiondoes not make sure that satisfactory antireflective properties can beobtained in the ultraviolet region.

The application EP 1 174 734 discloses a spectacle lens comprising onits rear face a multilayered antireflective coating designed in such away that the reflection on the antireflective coating surface be loweras compared to the one on the bare optical article surface within the280-700 nm wavelength range. The function of this antireflective coatingconsists in minimizing the reflection of the UV radiation originatingfrom behind the wearer or reflected by the wearer's face, on the lensrear face, so as to prevent the same from reaching the wearer's eye.

The antireflective coatings described in this application are veryefficient in the ultraviolet region. However, it would be advisable toimprove their mean reflection factors in the visible region. Moreover,the conceived stacks are sometimes relatively sophisticated, as they mayhave up to 10 layers.

The more numerous the number of layers, the easier the production of anefficient antireflective coating within a broad wavelength range.However, making such complicated antireflective coatings is not sointeresting from the economical point of view, since it requires ahigher amount of materials and makes the industrial process last longer.

The application WO 97/28467 discloses a transparent photochromic articlecomprising a photochromic substrate coated with atetra-layer-antireflective stack HI/LI/HI/LI, where HI refers to a layerwith a high refractive index and LI to a layer with a low refractiveindex. Such coating is designed so as not to interfere with the behaviorof the photochromic compounds that are present in or onto the substrate,by minimizing the reflection between 350 and 400 nm, which is thewavelength range enabling their activation. The thus preparedantireflective coatings are efficient in the UVA region, but thisproperty is accompanied with a significant decrease in theantireflective performances in the visible region.

The patent U.S. Pat. No. 4,852,974 discloses an optical articlecomprising a photochromic substrate and a multilayered antireflectivecoating, having a mean reflection factor between 290 nm and 330 nmhigher than 15% and a mean reflection factor between 330 nm and 380 nmthat is lower than 4% for an angle of incidence that was notcommunicated. Such antireflective coating makes it possible to extendthe life-time of the photochromic compounds contained in the substrate,but is relatively inefficient within a range where the UV radiationrelative efficiency is the highest (290-300 nm). Moreover, it would bedesirable to improve its performances in the visible region.

The application WO 2010/125 667 discloses a spectacle lens provided onits rear face with an antireflective coating enabling to reduce thereflection on the lens rear face of the UV radiation originating frombehind the wearer, so that it cannot reach his eye.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide atransparent optical article, especially an ophthalmic lens, comprising asubstrate in mineral or organic glass comprising on its rear face ananti-UV, antireflective coating possessing very good antireflectiveperformances in the visible region, and which is at the same timecapable of significantly reducing the UV radiation reflection,especially ultraviolet A- and ultraviolet B-rays, as compared to a baresubstrate or to a substrate comprising a traditional antireflectivecoating, and which production is easy at industrial scale.

The present invention provides an antireflective coating with animproved conception, comprising a stack made of thin layers, thethicknesses and materials of which have been selected so as to obtainsatisfactory antireflective performances both in the visible region andin the ultraviolet region.

The ultraviolet solar radiation distribution is tempered by the relativespectral efficiency of the UV solar radiation, which is nil or almostnil in the range of from 280 to 295 nm (which belongs to the ultravioletB-ray region). The present invention provides an antireflective coatingwith lower antireflection performances within this wavelength region,thus allowing to obtain an antireflective coating that is very efficientin the visible region and in the part of the ultraviolet range where thesolar radiation distribution tempered by the relative spectralefficiency of such radiation is high for the wearer (300-320 nm). Theantireflective coatings according to the invention thus tolerate ahigher spectral reflection in the 280 to 295 nm region, with noconsequence on the wearer.

The invention therefore relates to an optical article, preferably anophthalmic lens, comprising a substrate with a front main face and witha rear main face, said rear main face being coated with a multilayeredantireflective coating comprising a stack of at least one layer having arefractive index higher than 1.6 and at least one layer having arefractive index lower than 1.5, such that:

-   -   the mean reflection factor on said rear face in the visible        region R_(m) is lower than or equal to 1.15%,    -   the mean light reflection factor on said rear face in the        visible region R_(v) is lower than or equal to 1%,    -   the mean reflection factor R_(UV) on said rear face between 280        nm and 380 nm, weighted by the function W(λ) defined in the ISO        13666:1998 standard, is lower than 5%, for an angle of incidence        of 30° and for an angle of incidence of 45°,    -   the multilayered antireflective coating comprises a number of        layers higher than or equal to 3 and lower than or equal to 7,        preferably lower than or equal to 6, more preferably lower than        or equal to 5,    -   the multilayered antireflective coating does not comprise any        electrically conductive layer with a thickness higher than or        equal to 20 nm based on indium oxide,    -   the antireflective coating outer layer is a silica-based layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described in more detail by referring tothe appended drawings, wherein FIGS. 1 to 4 show the variation as afunction of the reflection wavelength on the surface of the rear face ofsome lenses prepared in the examples of the present application, for anangle of incidence of 15°, 30° and 45°.

DETAILED DESCRIPTION

In the present application, when an optical article comprises one ormore coatings onto the surface thereof, the expression “to deposit alayer or a coating onto the article” is intended to mean that a layer ora coating is deposited onto the external (exposed) surface of the outercoating of the article, that is to say its coating that is the mostdistant from the substrate.

A coating, that is said to be “on” a substrate or deposited “onto” asubstrate is defined as a coating, which (i) is positioned above thesubstrate, (ii) is not necessarily in contact with the substrate, thatis to say one or more intermediate coatings may be arranged between thesubstrate and the coating in question, and (iii) does not necessarilycompletely cover the substrate.

In a preferred embodiment, the coating on a substrate or deposited ontoa substrate is in direct contact with this substrate.

When “a layer 1 is lying under a layer 2”, it is intended to mean thatlayer 2 is more distant from the substrate than layer 1.

As used herein, the rear (or the inner) face of the substrate isintended to mean the face which, when using the article, is the nearestfrom the wearer's eye. It is generally a concave face. On the contrary,the front face of the substrate, is the face which, when using thearticle, is the most distant from the wearer's eye. It is generally aconvex face.

Generally speaking, the antireflective coating of the optical articleaccording to the invention, which will be called the “anti-UV,antireflective coating”, may be deposited onto any substrate, andpreferably onto organic lens substrates, for example a thermoplastic orthermosetting plastic material.

Thermoplastic materials to be suitably used for the substrates include(meth)acrylic (co)polymers, especially methyl poly(methacrylate) (PMMA),thio(meth)acrylic (co)polymers, polyvinylbutyral (PVB), polycarbonates(PC), polyurethanes (PU), poly(thiourethanes), polyol allylcarbonate(co)polymers, thermoplastic copolymers of ethylene/vinyl acetate,polyesters such as polyethylene terephthalate (PET) or polybutyleneterephthalate (PBT), polyepisulfides, polyepoxides,polycarbonate/polyester copolymers, cycloolefin copolymers such ascopolymers of ethylene/norbornene or ethylene/cyclopentadiene, andcombinations thereof.

As used herein, a (co)polymer is intended to mean a copolymer or apolymer. As used herein, a (meth)acrylate is intended to mean anacrylate or a methacrylate. As used herein, a polycarbonate (PC) isintended to mean either homopolycarbonates or copolycarbonates and blockcopolycarbonates.

Particularly recommended substrates include those substrates obtainedthrough (co)polymerization of the diethyleneglycol bis-allyl-carbonate,marketed, for example, under the trade name CR-39® by the PPG Industriescompany (ORMA® lenses, ESSILOR), or through polymerization of thethio(meth)acrylate monomers, such as those described in the applicationof the French patent FR 2 734 827. The substrates may be obtainedthrough polymerization of the above monomer combinations, or may furthercomprise mixtures of such polymers and (co)polymers.

Prior to depositing the antireflective coating onto the optionallycoated substrate, for example with an abrasion-resistant layer and/or ascratch-resistant coating or with a sub-layer, the surface of saidoptionally coated substrate is usually submitted to a physical orchemical surface activating treatment, so as to reinforce the adhesionof the antireflective coating. Such pre-treatment is generally conductedunder vacuum. It may be a bombardment with energetic and/or reactivespecies, for example with an ion beam (“Ion Pre-Cleaning” or “IPC”) orwith an electron beam, a corona discharge treatment, an ion spallationtreatment, an ultraviolet treatment or a plasma-mediated treatment undervacuum, generally using an oxygen or an argon plasma. It may also be anacid or basic treatment and/or a solvent-based treatment (water,hydrogen peroxide or any organic solvent).

In the present application, the “mean reflection factor,” noted R_(m),is such as defined in the ISO 13666:1998 Standard, and measured inaccordance with the ISO 8980-4 Standard (for an angle of incidence lowerthan 17°, typically of 15°), i.e. this is the (non weighted) spectralreflection average over the whole visible spectrum between 400 and 700nm.

The “mean light reflection factor,” noted R_(v), is such as defined inthe ISO 13666:1998 Standard, and measured in accordance with the ISO8980-4 Standard (for an angle of incidence lower than 17°, typically of15°), i.e. this is the weighted spectral reflection average over thewhole visible spectrum between 380 and 780 nm.

The mean reflection factor between 290 and 330 nm, noted R_(m-UV1) canbe defined by analogy, which corresponds to the mean spectral reflectionbetween 290 and 330 nm. According to the invention, this factor may bemeasured at an angle of incidence that may range from 30 to 45°.Similarly, the mean reflection factors in the UVA and UVB ranges, notedR_(m-UVA) and R_(m-UVB), are defined, the sum of which corresponds tothe mean reflection factor in the ultraviolet region (280-380 nm), notedR_(m-UV).

Lastly, the mean reflection factor between 280 nm and 380 nm, weightedby the W(λ) function defined according to the ISO 13666:1998 Standardand noted R_(UV), may be defined through the following relation:

$R_{UV} = \frac{\int_{280}^{380}{{W(\lambda)} \cdot {R(\lambda)} \cdot \ {\lambda}}}{\int_{280}^{380}{{W(\lambda)} \cdot {\lambda}}}$

wherein R(λ) represents the lens spectral reflection factor at a givenwavelength, and W(λ) represents a weighting function equal to theproduct of the solar spectrum irradiance Es(λ) and the efficiencyrelative spectral function S(λ).

The spectral function W(λ), enabling to calculate the ultravioletradiation transmission factors, is defined according to the ISO13666:1998 Standard. It makes it possible to express the ultravioletsolar radiation distribution tempered by the relative spectralefficiency of such radiation for the wearer, since it simultaneouslytakes both the solar spectral energy Es(λ) into account, which doesglobally emit less UVB-rays as compared to UVA-rays, and the spectralefficiency S(λ), UVB-rays being more harmful than UVA-rays. The valuesfor those three functions in the ultraviolet region are given in thefollowing table:

Wave- Solar spectrum Efficiency relative Weighting function length λirradiance Es(λ) spectral function W(λ) = (nm) (mW/m² · nm) S(λ) Es(λ) ·S(λ) 280 0 0.88 0 285 0 0.77 0 290 0 0.64 0 295 2.09 × 10⁻⁴ 0.54 0.00011300 8.10 × 10⁻² 0.30 0.0243 305 1.91 0.060 0.115 310 11.0 0.015 0.165315 30.0 0.003 0.09 320 54.0 0.0010 0.054 325 79.2 0.00050 0.04 330 1010.00041 0.041 335 128 0.00034 0.044 340 151 0.00028 0.042 345 1700.00024 0.041 350 188 0.00020 0.038 355 210 0.00016 0.034 360 2330.00013 0.03 365 253 0.00011 0.028 370 279 0.000093 0.026 375 3060.000077 0.024 380 336 0.000064 0.022

It should be noted that the weighting function W(λ) is nil or almost nilbetween 280 nm and 295 nm, which means that the weighted mean reflectionfactor is also nil within this wavelength range. This means that even ifthe reflection level is high over this spectral range, there will be noconsequence on the weighted mean reflection factor value R_(UV)calculated between 280 and 380 nm.

According to the present invention, the antireflective coating depositedonto the rear face of the substrate is such that:

-   -   the mean reflection factor R_(UV) on said rear face between 280        nm and 380 nm, weighted by the function W(λ) defined according        to the ISO 13666:1998 Standard, is lower than 5%, for an angle        of incidence of 30° and for an angle of incidence of 45°. For        these angles of incidence, it is preferably lower than or equal        to one of the following values: 4.5%, 4%, 3.5%, 3%, 2.5%, 2%,        1.5%.    -   the mean reflection factor on said rear face in the visible        region R_(m) of the optical article is lower than or equal to        1.15%, preferably ≦1%, more preferably ≦0.75%, the mean light        reflection factor on said rear face in the visible region R_(v)        of the optical article is lower than or equal to 1%, preferably        ≦0.90%, more preferably ≦0.85%.

The anti-UV, antireflective coating according to the invention isespecially designed to minimize the reflection towards the eye of theultraviolet radiation having an angle of incidence on the lenses rangingfrom 30 to 45°, and its preferred characteristics are describedhereunder.

Preferably, the mean reflection factor R_(m-UV1) on said rear facebetween 290 nm and 330 nm is lower than 15%, for an angle of incidenceof 15°, preferably lower than 10%.

In a preferred embodiment of the invention, the mean reflection factoris higher than 5%, more preferably higher than 6%, even more preferablyhigher than 8% over at least 20% of the 280-295 nm wavelength range, foran angle of incidence of 30° and for an angle of incidence of 45°.

In a further preferred embodiment, the mean reflection factor over atleast 70%, more preferably at least 80%, and even more preferably over100% of the 280-295 nm wavelength range for an angle of incidence of15°, is higher than 10%, preferably higher than 15%.

In another embodiment, the mean reflection factor on the rear face overat least 70%, more preferably at least 80%, and even more preferablyover 100% of the 280-290 nm wavelength range for an angle of incidenceof 15°, is higher than 10%, preferably higher than 15%.

Within such wavelength range, the weighting function W(λ) is nil oralmost nil. In another embodiment, the mean reflection factor is higherthan 5%, more preferably higher than 6%, even more preferably higherthan 10%, for at least one wavelength in the 280-295 nm range, for anangle of incidence of 30° and for an angle of incidence of 45°.

Since the mean reflection factor is higher in the 280-295 nm wavelengthrange or in the 280-290 nm wavelength range, the antireflectiveproperties can be improved in another part of the spectral range, namelyin the visible range.

Preferably, the mean reflection factor R_(m-UV2) on said rear facebetween 300 nm and 320 nm is lower than 4%, more preferably lower than3%, for an angle of incidence of 15° and/or 30° and/or 45°. This isparticularly interesting for the lens wearer, because the weightingfunction W(λ) defined according to the ISO 13666:1998 Standard is veryhigh within such ultraviolet region wavelength range, and reaches amaximum level at 310 nm.

Preferably, the mean reflection factor R_(m-UV3) on said rear facebetween 300 nm and 380 nm is lower than 5%, more preferably lower than4.5%, for an angle of incidence of 15°.

The person skilled in the art, with its general knowledge is fullycapable of choosing the suitable materials and thicknesses for thevarious layers of the antireflective coating so as to have the differentdesired parameters R_(m-UV1), R_(m-UV2), R_(m-UV3), R_(UV), R_(m) andR_(v).

The multilayered antireflective coating of the invention comprises astack of at least one layer with a high refractive index and of at leastone layer with a low refractive index. More preferably, it comprises atleast two layers with a low refractive index (LI) and at least twolayers with a high refractive index (HI). It is here a simple stack,since the layer total number in the antireflective coating is higherthan or equal to 3, preferably higher than or equal to 4, and lower thanor equal to 7, more preferably lower than or equal to 6, even morepreferably lower than or equal to 5, and most preferably equal to 5layers.

As used herein, a layer of the antireflective coating is defined ashaving a thickness higher than or equal to 1 nm. Thus, any layer havinga thickness lower than 1 nm will not be considered when counting thenumber of layers in the antireflective coating. The sub-layer either isnot considered when counting the number of layers of the antireflectivecoating.

Unless stated otherwise, all thicknesses disclosed in the presentapplication relate to physical thicknesses.

HI layers and BI layers don't need to alternate with each other in thestack, although they also may, according to one embodiment of theinvention. Two HI layers (or more) may be deposited onto each other, aswell as two LI layers (or more) may be deposited onto each other.

In the present application, a layer of the antireflective coating issaid to be a layer with a high refractive index (HI) when its refractiveindex is higher than 1.6, preferably higher than or equal to 1.65, evenmore preferably higher than or equal to 1.7, even more preferably higherthan or equal to 1.8 and most preferably higher than or equal to 1.9.Said HI layer preferably has a refractive index lower than 2.1. A layerof an antireflective coating is said to be a low refractive index layer(LI) when its refractive index is lower than or equal to 1.50,preferably lower than or equal to 1.48, more preferably lower than orequal to 1.47. Said LI layer preferably has a refractive index higherthan 1.1.

Unless otherwise specified, the refractive indexes referred to in thepresent application are expressed at 25° C. at a wavelength of 550 nm.

The HI layer is a traditional high refractive index layer, that is wellknown in the art. It generally comprises one or more metal oxides suchas, without limitation, zirconia (ZrO₂), titanium dioxide (TiO₂),alumina (Al₂O₃), tantalum pentoxide (Ta₂O₅), neodymium oxide (Nd₂O₅),praseodymium oxide (Pr₂O₃), praseodymium titanate (PrTiO₃), La₂O₃,Nb₂O₅, Y₂O₃. Optionally, the HI layers may further contain silica orother materials with a low refractive index, provided they have arefractive index higher than 1.6 as indicated hereabove. The preferredmaterials include TiO₂, PrTiO₃, ZrO₂, Al₂O₃, Y₂O₃ and mixtures thereof.

The LI layer is also well known and may comprise, without limitation,SiO₂, or a mixture of silica and alumina, especially silica doped withalumina, the latter contributing to increase the antireflective coatingthermal resistance. The LI layer is preferably a layer comprising atleast 80% by weight of silica, more preferably at least 90% by weight ofsilica, relative to the layer total weight, and even more preferablyconsists in a silica layer. Preferably, the LI layers in theantireflective coating are not MgF₂ layers.

Optionally, the LI layers may further contain materials with a highrefractive index, provided the refractive index of the resulting layeris lower than or equal to 1.5.

When a LI layer comprising a mixture of SiO₂ and Al₂O₃ is used, itpreferably comprises from 1 to 10%, more preferably from 1 to 8% andeven more preferably from 1 to 5% by weight of Al₂O₃ relative to theSiO₂+Al₂O₃ total weight in such layer.

For example, SiO₂ doped with 4% Al₂O₃ by weight, or less, or SiO₂ dopedwith 8% Al₂O₃ may be employed. SiO₂/Al₂O₃ mixtures, that are availableon the market may be used, such as LIMA® marketed by the UmicoreMaterials AG company (refractive index n=1.48-1.50 at 550 nm), or L5®marketed by the Merck KGaA company (refractive index n=1.48 at 500 nm).

The antireflective coating outer layer is necessarily a silica-basedlayer, comprising preferably at least 80% by weight of silica, morepreferably at least 90% by weight of silica (for example a silica layerdoped with alumina), relative to the layer total weight, and even morepreferably consists in a silica layer.

Generally, the HI layers have a physical thickness ranging from 10 to120 nm, and the LI layers have a physical thickness ranging from 10 to100 nm.

Generally, the antireflective coating total thickness is lower than 1micrometer, preferably lower than or equal to 800 nm, more preferablylower than or equal to 500 nm and even more preferably lower than orequal to 250 nm. The antireflective coating total thickness is generallyhigher than 100 nm, preferably higher than 150 nm.

Preferably, the antireflective coating does not comprise any layercomprising titanium oxide with a thickness higher than 90 nm, preferablyhigher than 70 nm. When several layers comprising titanium oxide arepresent in the antireflective coating, their total thickness ispreferably lower than 90 nm, more preferably lower than 70 nm. Mostpreferably, the antireflective coating does not comprise any titaniumoxide-containing layer. The titanium oxide-containing layers are indeedsensitive to photodegradation. As used herein, titanium oxide isintended to mean titanium dioxide or a substoichiometric titanium oxide(TiOx, where x<2).

In one embodiment of the present invention, the antireflective coatingis deposited onto a sub-layer. It should be noted that suchantireflective coating sub-layer does not belong to the antireflectivecoating.

As used herein, an antireflective coating sub-layer or adhesion layer isintended to mean a relatively thick coating, used in order to improvethe mechanical properties such as the abrasion resistance and/or thescratch resistance of said coating and/or so as to reinforce itsadhesion to the substrate or to the underlying coating.

Because of its relatively high thickness, the sub-layer does notgenerally take part to the antireflective optical activity, especiallywhen it has a refractive index close to that of the underlying coating(which is generally the anti-abrasion and anti-scratch coating) or tothat of the substrate, if the sub-layer is directly deposited onto thesubstrate.

The sub-layer should have a thickness that is sufficient for promotingthe abrasion resistance of the antireflective coating, but preferablynot to such an extent that a light absorption could be caused, which,depending on the sub-layer nature, could significantly reduce therelative transmission factor τ_(v). Its thickness is generally lowerthan 300 nm, more preferably lower than 200 nm, and is generally higherthan 90 nm, more preferably higher than 100 nm.

The sub-layer preferably comprises a SiO₂—based layer, this layercomprising preferably at least 80% by weight of silica, more preferablyat least 90% by weight of silica, relative to the layer total weight,and even more preferably consists in a silica layer. The thickness ofsuch silica-based layer is generally lower than 300 nm, more preferablylower than 200 nm, and is generally higher than 90 nm, more preferablyhigher than 100 nm.

In another embodiment, this SiO₂—based layer is a silica layer dopedwith alumina, in amounts such as defined hereabove, preferably consistsin a silica layer doped with alumina.

In a particular embodiment, the sub-layer consists in a SiO₂ layer.

A sub-layer of the monolayer type will be preferably used. However, thesub-layer may be laminated (multilayered), especially when the sub-layerand the underlying coating (or the substrate, if the sub-layer isdeposited directly onto the substrate) have a substantially differentrefractive index. This applies especially when the underlying coating,which is generally an anti-abrasion and/or anti-scratch coating, or thesubstrate, have a high refractive index, i.a. a refractive index higherthan or equal to 1.55, preferably higher than or equal to 1.57.

In this case, the sub-layer may comprise, in addition to a 90-300nm-thick layer, called the main layer, preferably at most threeadditional layers, more preferably at most two additional layers,interleaved between the optionally coated substrate and such 90-300nm-thick layer, which is generally a silica-based layer. Theseadditional layers are preferably thin layers, which function aims atlimiting the reflections at the sub-layer/underlying coating interfaceor sub-layer/substrate interface, as appropriate.

A multilayered sub-layer preferably comprises, in addition to the mainlayer, a layer with a high refractive index and with a thickness lowerthan or equal to 80 nm, more preferably lower than or equal to 50 nm andmost preferably lower than or equal to 30 nm. Such layer with a highrefractive index is directly contacting the substrate with a highrefractive index or the underlying coating with a high refractive index,as appropriate. Of course, this embodiment may be used even if thesubstrate (or the underlying coating) has a refractive index lower than1.55.

As an alternative, the sub-layer comprises, in addition to the mainlayer and to the previously mentioned layer with a high refractiveindex, a layer made of a SiO₂-based material (that is to say comprisingpreferably at least 80% by weight of silica) with a refractive indexlower than or equal to 1.55, preferably lower than or equal to 1.52,more preferably lower than or equal to 1.50, and with a thickness lowerthan or equal to 80 nm, more preferably lower than or equal to 50 nm andeven more preferably lower than or equal to 30 nm, onto which isdeposited said layer with a high refractive index. Typically, in thisinstance, the sub-layer comprises, deposited in this order onto theoptionally coated substrate, a 25 nm-thick SiO₂ layer, a 10 nm-thickZrO₂ or Ta₂O₅ layer and thereafter the sub-layer main layer.

The optical article of the invention may be made antistatic, that is tosay not to retain and/or develop a substantial static charge, byincorporating at least one electrically conductive layer into the stackpresent on the surface of the article.

The ability for a glass to evacuate a static charge obtained afterrubbing with a piece of cloth or using any other procedure to generate astatic charge (charge applied by corona . . . ) may be quantified bymeasuring the time it takes for said charge to dissipate. Thus,antistatic glasses have a discharge time of about a few hundredmilliseconds, preferably 500 ms or less, whereas it is of about severaltens of seconds for a static glass. In the present application,discharge times are measured according to the method exposed in theFrench application FR 2 943 798.

As used herein, an “electrically conductive layer” or an “antistaticlayer” is intended to mean a layer which, due to its presence on thesurface of a non-antistatic substrate (i.e. having a discharge timehigher than 500 ms), enables to have a discharge time of 500 ms or lessafter a static charge has been applied onto the surface thereof.

The electrically conductive layer may be located on various places inthe stack, generally in or in contact with the antireflective coating,provided the anti-reflective properties thereof are not affected. It ispreferably located between two layers of the antireflective coating,and/or is adjacent to a layer with a high refractive index of suchantireflective coating. Preferably, the electrically conductive layer islocated immediately under a layer with a low refractive index of theantireflective coating, most preferably is the penultimate layer of theantireflective coating by being located immediately under thesilica-based outer layer of the antireflective coating.

The electrically conductive layer should be thin enough not to alter thetransparency of the antireflective coating. The electrically conductivelayer is preferably made from an electrically conductive and highlytransparent material, generally an optionally doped metal oxide. In thiscase, the thickness thereof preferably varies from 1 to 15 nm, morepreferably from 1 to 10 nm. Preferably, the electrically conductivelayer comprises an optionally doped metal oxide, selected from indium,tin, zinc oxides and mixtures thereof. Tin-indium oxide (In₂O₃:Sn,tin-doped indium oxide), aluminium-doped zinc oxide (ZnO:Al), indiumoxide (In₂O₃) and tin oxide (SnO₂) are preferred. In a most preferredembodiment, the electrically conductive and optically transparent layeris a tin-indium oxide layer, noted ITO layer or a tin oxide layer.

Generally, the electrically conductive layer contributes, within thestack, but in a limited manner, because of its low thickness, toobtaining antireflective properties and represents a layer with a highrefractive index in the antireflective coating. This is the case forthose layers made from an electrically conductive and highly transparentmaterial such as ITO layers.

The antireflective coating does not comprise any layer with a thicknesshigher than or equal to 20 nm, preferably higher than 15 nm, based onindium oxide. When a plurality of indium oxide-based layers are presentin the antireflective coating, their total thickness is preferably lowerthan 20 nm, more preferably lower than 15 nm. As used herein, an indiumoxide-based layer is intended to mean a layer comprising at least 50% byweight of indium oxide relative to the layer total weight.

According to a preferred embodiment, the antireflective coating does notcomprise any layer with a thickness higher than or equal to 20 nm,preferably higher than 15 nm, comprising indium oxide, tin oxide or zincoxide. When a plurality of layers comprising indium oxide, tin oxide orzinc oxide are present in the antireflective coating, their totalthickness is preferably lower than 20 nm, more preferably lower than 15nm.

The various layers of the antireflective coating and the optionalsub-layer are preferably deposited by chemical vapor deposition, undervacuum, according to any of the following methods: i) by optionallyion-beam assisted, evaporation; ii) by ion-beam sputtering; iii) bycathode sputtering; iv) by plasma-assisted chemical vapor deposition.These various methods are described in the following references “ThinFilm Processes” and “Thin Film Processes II,” Vossen & Kern, Ed.,Academic Press, 1978 and 1991, respectively. A particularly recommendedmethod is the evaporation under vacuum.

Preferably, the deposition of each of the layers of the antireflectivecoating and of the optional sub-layer is conducted by evaporation undervacuum.

Preferably, the antireflective coating of the invention comprises afirst layer or superposition of layers consisting in 1, 2 or 3 layershaving a refractive index higher than 1.6 coated with a second layer orsuperposition of layers consisting in 1 or 2 layers having a refractiveindex lower than 1.5. Optionally, this second layer or superposition oflayers is coated with a third layer or superposition of layersconsisting in 1 or 2 layers having a refractive index higher than 1.6,itself coated with a fourth layer or superposition of layers consistingin 1 or 2 layers having a refractive index lower than 1.5.

According to a particularly preferred embodiment, the anti-UV,antireflective coating comprises, starting from the surface of thesubstrate optionally coated with one or more functional coatings andpreferably coated with a 100-200 nm-thick sub-layer, preferably ofsilica, a layer with a high refractive index with a thickness of from 8to 25 nm, preferably of from 8 to 20 nm, preferably of zirconia, a layerwith a low refractive index with a thickness of from 10 to 35 nm,preferably of from 15 to 25 nm, preferably of silica, a layer with ahigh refractive index with a thickness of from 75 to 105 nm, preferablyof from 75 to 100 nm, more preferably of from 85 to 100 nm, even morepreferably of from 90 to 100 nm, preferably of zirconia, optionally anelectrically conductive layer with a thickness of from 3 to 10 nm,preferably of from 4 to 8 nm and a layer with a low refractive indexwith a thickness of from 60 to 95 nm, preferably of from 65 to 90 nm,more preferably of from 70 to 95 nm, preferably of silica.

In another embodiment, the anti-UV, antireflective coating comprises,starting from the surface of the substrate optionally coated with one ormore functional coatings and coated preferably with a 100-200 nm-thicksub-layer, preferably of silica, a layer with a high refractive indexwith a thickness of from 20 to 65 nm, preferably of zirconia, a layerwith a low refractive index with a thickness of from 10 to 30 nm,preferably of silica, a layer with a high refractive index with athickness of from 5 to 75 nm, preferably of zirconia, a layer with ahigh refractive index with a thickness of from 20 to 75 nm, preferablyof titanium, optionally an electrically conductive layer with athickness of from 3 to 10 nm, preferably of from 4 to 8 nm and a layerwith a low refractive index with a thickness of from 60 to 85 nm,preferably of silica.

In a preferred embodiment of the invention, the front face of theoptical article of the invention is also coated with a conventionalantireflective coating, different from the one provided on its rearface.

In this case, it is possible for the front face of the optical articleto be coated with an antireflective coating that is more efficient inthe visible region than that of the substrate's rear face. Thus, in apreferred embodiment, the front face of the optical article is coatedwith an antireflective coating so that the mean reflection factor in thevisible region R_(m) on this front face is lower than 0.8%, morepreferably lower than 0.5%. Preferably, the mean light reflection factorR_(v) on this front face is lower than 0.8%, more preferably lower than0.5%. Still preferably, the mean reflection factor R_(UV) between 280 nmand 380 nm, weighted by the function W(λ) as defined according to theISO 13666:1998 Standard, is higher on the front face (preferably >5%)than on the rear face of the optical article.

In a preferred embodiment, for the front face (convex) of the opticalarticle, the mean reflection factor R_(UV) between 280 and 380 nm for anangle of incidence of 45° weighted by the function W(λ) definedaccording to the ISO 13666:1998 Standard, is higher than 7%, morepreferably higher than 8%, even more preferably higher than 10% and mostpreferably higher than 12%.

The mean reflection factor R_(UV) between 280 and 380 nm for the frontface (convex) of the optical article and for an angle of incidence of45°, weighted by the function W(λ) defined according to the ISO13666:1998 Standard, may preferably have values higher than 15%, morepreferably higher than 20%, even more preferably higher than 30%.

When a coating is used, which on the front face has a mean reflectionfactor R_(UV) between 280 and 380 nm for an angle of incidence of 45°,weighted by the function W(λ) defined according to the ISO 13666:1998Standard, higher than 5%, and within the hereabove mentioned preferredranges, it is preferred to combine therewith, on the rear face, theantireflective coating of the invention (such as defined in the appendedclaims), having in addition the following preferred characteristics:

The mean reflection factor on said rear face is higher than 5%, morepreferably higher than 6%, even more preferably higher than 8%, over atleast 20% of the 280 to 295 nm wavelength range, for an angle ofincidence of 30° and for an angle of incidence of 45°.

In another preferred embodiment, on the rear face, the mean reflectionfactor, over at least 70%, preferably over at least 80% and even morepreferably over 100% of the 280 to 295 nm-wavelength range, for an angleof incidence of 15°, is higher than 10%, preferably higher than 15%.

In still another embodiment, on the rear face, the mean reflectionfactor, over at least 70%, preferably over at least 80% and even morepreferably over 100% of the 280 to 290 nm-wavelength range, for an angleof incidence of 15°, is higher than 10%, preferably higher than 15%.

The antireflective coating of the front face comprises preferably astack of at least one layer with a high refractive index and of at leastone layer with a low refractive index.

It is however possible to apply an anti-UV, antireflective coating suchas described in the present application on the front face of the opticalarticle. The anti-UV antireflective coatings of the front face and ofthe rear face may then be the same or different.

In one embodiment of the present invention, the front face of theoptical article is not coated with an anti-UV, antireflective coatingaccording to the invention.

The anti-UV, antireflective coating may be deposited directly onto abare substrate. In some applications, it is preferred for the main faceof the substrate to be coated with one or more functional coatings priorto depositing the antireflective coating of the invention. Thesefunctional coatings traditionally used in optics may be, withoutlimitation, an impact-resistant primer layer, an abrasion-resistantcoating and/or a scratch-resistant coating, a polarizing coating, aphotochromic coating or a tinted coating.

Preferably, the ophthalmic lens does not comprise any photochromiccoating and/or does not comprise any photochromic substrate.

Generally, the front and/or rear main face of the substrate onto whichan antireflective coating will be deposited is coated with animpact-resistant primer layer, with an anti-abrasion and/or anti-scratchcoating, or with an impact-resistant primer layer coated with ananti-abrasion and/or anti-scratch coating.

The anti-UV, antireflective coating of the invention is preferablydeposited onto an anti-abrasion and/or anti-scratch coating. Theanti-abrasion and/or scratch-resistant coating may be any layertraditionally used as an anti-abrasion and/or anti-scratch coating inthe field of ophthalmic lenses.

The anti-abrasion and/or scratch-resistant coatings are preferably hardcoatings based on poly(meth)acrylates or silanes, generally comprisingone or more mineral fillers intended to increase the hardness and/or therefractive index of the coating once cured.

Hard anti-abrasion and/or scratch-resistant coatings are preferablyprepared from compositions comprising at least one alkoxysilane and/or ahydrolyzate thereof, obtained for example through hydrolysis with ahydrochloric acid solution and optionally condensation and/or curingcatalysts.

Suitable coatings, that are recommended for the present inventioninclude coatings based on epoxysilane hydrolyzates such as thosedescribed in the patents FR 2 702 486 (EP 0 614 957), U.S. Pat. No.4,211,823 and U.S. Pat. No. 5,015,523.

A preferred anti-abrasion and/or scratch-resistant coating compositionis the one disclosed in the patent FR 2 702 486, in the name of theapplicant. It comprises a hydrolyzate of epoxy trialkoxysilane anddialkyl dialkoxysilane, colloidal silica and a catalytic amount of analuminium-based curing catalyst such as aluminium acetylacetonate, therest being essentially composed of solvents traditionally used forformulating such compositions. Preferably, the hydrolyzate used is ahydrolyzate of γ-glycidoxypropyltrimethoxysilane (GLYMO) anddimethyldiethoxysilane (DMDES).

The anti-abrasion and/or scratch-resistant coating composition may bedeposited onto the main face of the substrate by dip- or spin-coating.It is then cured by a suitable method (preferably using heat orultraviolet radiation).

The thickness of the anti-abrasion and/or scratch-resistant coating doesgenerally vary from 2 to 10 μm, preferably from 3 to 5 μm.

Prior to depositing the abrasion-resistant coating and/or thescratch-resistant coating, it is possible to apply onto the substrate aprimer coating to improve the impact resistance and/or the adhesion ofthe subsequent layers in the final product. This coating may be anyimpact-resistant primer layer traditionally used for articles in atransparent polymer material, such as ophthalmic lenses.

Preferred primer compositions include compositions based onthermoplastic polyurethanes, such as those described in the Japanesepatents JP 63-141001 and JP 63-87223, poly(meth)acrylic primercompositions, such as those described in the patent U.S. Pat. No.5,015,523, compositions based on thermosetting polyurethanes, such asthose described in the patent EP 0 404 111 and compositions based onpoly(meth)acrylic latexes or polyurethane type latexes, such as thosedescribed in the patents U.S. Pat. No. 5,316,791 and EP 0 680 492.

Preferred primer compositions are compositions based on polyurethanesand compositions based on latexes, especially polyurethane type latexesoptionally containing polyester units.

Commercially available primer compositions to be suitably used in thepresent invention include compositions such as Witcobond® 232,Witcobond® 234, Witcobond® 240, Witcobond® 242, Neorez® R-962, Neorez®R-972, Neorez® R-986 and Neorez® R-9603.

Combinations of such latexes may also be used in the primer, especiallyof polyurethane type latexes and poly(meth)acrylic latexes.

Such primer compositions may be deposited onto the article faces by dip-or spin-coating, thereafter be dried at a temperature of at least 70° C.and up to 100° C., preferably of about 90° C., for a time period rangingfrom 2 minutes to 2 hours, generally of about 15 minutes, to form primerlayers having thicknesses, after curing, of from 0.2 to 2.5 μm,preferably of from 0.5 to 1.5 μm.

The optical article according to the invention may also comprisecoatings formed on the antireflective coating and capable of modifyingthe surface properties thereof, such as hydrophobic and/or oleophobiccoatings (antifouling top coat). These coatings are preferably depositedonto the outer layer of the antireflective coating. As a rule, theirthickness is lower than or equal to 10 nm, does preferably range from 1to 10 nm, more preferably from 1 to 5 nm.

There are generally coatings of the fluorosilane or fluorosilazane type.They may be obtained by depositing a fluorosilane or fluorosilazaneprecursor, comprising preferably at least two hydrolyzable groups permolecule. Fluorosilane precursors preferably comprise fluoropolyethermoieties and more preferably perfluoropolyether moieties. Thesefluorosilanes are well known and are described, between others, in thepatents U.S. Pat. No. 5,081,192, U.S. Pat. No. 5,763,061, U.S. Pat. No.6,183,872, U.S. Pat. No. 5,739,639, U.S. Pat. No. 5,922,787, U.S. Pat.No. 6,337,235, U.S. Pat. No. 6,277,485 and EP 0 933 377.

A preferred hydrophobic and/or oleophobic coating composition ismarketed by Shin-Etsu Chemical under the trade name KP 801 M®. Anotherpreferred hydrophobic and/or oleophobic coating composition is marketedby Daikin Industries under the trade name OPTOOL DSX®. It is afluorinated resin comprising perfluoropropylene groups.

Instead of the hydrophobic coating, a hydrophilic coating may be usedwhich provides antifog properties, or an antifog precursor coating whichprovides antifog properties when associated with a surfactant. Examplesof such antifog precursor coatings are described in the patentapplication WO 2011/080472.

Typically, an ophthalmic lens according to the invention comprises asubstrate that is successively coated on its rear face with animpact-resistant primer layer, an anti-abrasion and scratch-resistantlayer, an anti-UV, antireflective coating according to the invention,and with a hydrophobic and/or oleophobic coating, or with a hydrophiliccoating which provides antifog properties, or an antifog precursorcoating. The ophthalmic lens according to the invention is preferably anophthalmic lens for spectacles (spectacle lens), or a blank forophthalmic lenses. The lens may be a polarized lens, a photochromic lensor a solar lens, which may be tinted, be corrective, or not.

The front face of the substrate of the optical article may besuccessively coated with an impact-resistant primer layer, anabrasion-resistant layer and/or a scratch-resistant layer, anantireflective coating which may be, or not, an anti-UV, antireflectivecoating according to the invention, and with a hydrophobic and/oroleophobic coating.

In one embodiment, the optical article according to the invention doesnot absorb in the visible or not much, which means, in the context ofthe present application, that its transmission factor in the visiblerange τ_(v), also called relative transmission factor in the visiblerange, is higher than 90%, more preferably higher than 95%, even morepreferably higher than 96% and most preferably higher than 97%.

The factor τV should be understood as defined by the internationalnormalized definition (ISO 13666:1998 Standard) and is measured inaccordance with the ISO 8980-3 Standard. It is defined in the wavelengthrange of from 380 to 780 nm.

Preferably, the light absorption of the article coated according to theinvention is lower than or equal to 1%.

The colorimetric coefficients of the optical article of the invention inthe international colorimetric CIE L*a*b* are calculated between 380 and780 nm, taking the standard illuminant D 65 and the observer intoaccount (angle of incidence: 15°). It is possible to prepareantireflective coatings, without limitation as regards their hue angle.However, the hue angle h preferably varies from 120 to 150, thusresulting in a coating having a green reflection, and the chroma C* ispreferably lower than 15, more preferably lower than 10. It is much moredifficult to obtain an antireflective coating which performances havebeen optimized in the visible region and in the ultraviolet region whenthe hue angle lies within the 120-150° range (green) relative to the235-265° range (blue).

In one embodiment, the chroma C* is higher than 9. The inventorsobserved that in this instance, the ophthalmic lens has a greatcolorimetric reliability, i.e. the hue angle h and the chroma C* wereparticularly stable over time.

The following examples illustrate the present invention in a moredetailed, but non-limiting manner.

EXAMPLES 1. General Procedures

The optical articles used in the examples comprise an ORMA® lenssubstrate from ESSILOR, having a 65 mm diameter, a refractive index of1.50, and a power of −2.00 diopters and a thickness of 1.2 mm, coated onits rear face with the anti-abrasion and scratch-resistant coating (hardcoat) disclosed in Example 3 of the patent EP 0 614 957 (refractiveindex equal to 1.47 and thickness of 3.5 μm), based on a hydrolyzatecomposed of GLYMO and DMDES, of colloidal silica and aluminiumacetylacetonate, and thereafter with an antireflective coating accordingto the present invention.

Said anti-abrasion and scratch-resistant coating was obtained bydepositing and hardening a composition comprising by weight, 224 partsof GLYMO, 80.5 parts of HCl 0.1 N, 120 parts of DMDES, 718 parts of 30%by weight colloidal silica in methanol, 15 parts of aluminumacetylacetonate and 44 parts of ethylcellosolve. The composition alsocontained 0.1% of surfactant FLUORAD™ FC-430® manufactured by 3M, byweight relative to the composition total weight.

The layers of the antireflective coating were deposited without heatingthe substrates by evaporation under vacuum (evaporation source: electrongun).

The deposition frame is a Leybold 1104 machine fitted with an electrongun (ESV14 (8 kV)) for evaporating oxides, and provided with an ion gun(Commonwealth Mark II) for the preliminary phase to prepare the surfaceof the substrate using argon ions (IPC).

The thickness of the layers was controlled by means of a quartzmicrobalance. The spectral measurements were effected on a variableincidence-spectrophotometer Perkin-Elmer Lambda 850 with an URAaccessory (Universal Reflectance Accessory).

2. Test Procedure

The method for making optical articles comprises the step of introducingthe substrate, coated on its rear face with the anti-abrasion andscratch-resistant coating, into a vacuum deposition chamber, a step ofpumping until a high-vacuum is obtained, a step of activating thesurface of the substrate by means of an argon ion beam (anode current: 1A, anode voltage: 100 V, neutralization current: 130 mA), turning theion irradiation off, forming the sub-layer on the anti-abrasion andscratch-resistant coating, then subsequently the various layers of theantireflective coating by successive evaporations and at last aventilation step.

3. Results

The structural characteristics and the optical performances of theophthalmic lenses obtained in the Examples 1 to 26 are detailedhereunder. The sub-layer is gray-colored. The reflection graphs between280 and 780 nm of some articles prepared are illustrated on FIGS. 1-4,with various angles of incidence.

The reflection mean factor values are those of the rear face. FactorsR_(m) and R_(v) are provided for an angle of incidence of 15°.

Example 1 Example 2 Example 3 Substrate + hard coat Substrate + hardcoat Substrate + hard coat SiO₂ 150 nm  SiO₂ 150 nm  SiO₂ 150 nm  ZrO₂19 nm ZrO₂ 17 nm ZrO₂ 13 nm SiO₂ 23 nm SiO₂ 23 nm SiO₂ 14 nm ZrO₂ 93 nmZrO₂ 96 nm ZrO₂ 95 nm ITO 6.5 nm  ITO 6.5 nm  ITO 6.5 nm  SiO₂ 82 nmSiO₂ 75 nm SiO₂ 76 nm Air Air Air R_(UV) (%) 2.59 (30°) R_(UV) (%) 1.28(30°) R_(UV) (%) 3.68 (30°) 3.10 (45°) 1.64 (45°) 3.10 (45°) h (°) 135 h(°) 135 h (°) 250 C* 7 C* 6.9 C* 12 R_(m) (%) 0.58 R_(m) (%) 1.02 R_(m)(%) 1.04 R_(v) (%) 0.59 R_(v) (%) 0.85 R_(v) (%) 0.68 Example 4 Example5 Example 6 Substrate + hard coat Substrate + hard coat Substrate + hardcoat SiO₂ 150 nm  SiO₂ 150 nm  SiO₂ 150 nm  ZrO₂ 14 nm ZrO₂ 13 nm ZrO₂11 nm SiO₂ 25 nm SiO₂ 31 nm SiO₂ 33 nm ZrO₂ 93 nm ZrO₂ 87 nm ZrO₂ 90 nmITO 6.5 nm  ITO 6.5 nm  ITO 6.5 nm  SiO₂ 88 nm SiO₂ 86 nm SiO₂ 84 nm AirAir Air R_(UV) (%) 4.26 (30°) R_(UV) (%) 2.92 (30°) R_(UV) (%) 2.62(30°) 3.91 (45°) 3.15 (45°) 2.30 (45°) h (°) 250 h (°) 300 h (°) 300 C*8.5 C* 12 C* 15 R_(m) (%) 0.62 R_(m) (%) 0.73 R_(m) (%) 0.84 R_(v) (%)0.40 R_(v) (%) 0.23 R_(v) (%) 0.26 Example 7 Example 8 Example 9Substrate + hard coat Substrate + hard coat Substrate + hard coat SiO₂150 nm  SiO₂ 150 nm  SiO₂ 150 nm  ZrO₂ 10 nm ZrO₂ 9 nm ZrO₂ 16 nm SiO₂24 nm SiO₂ 22 nm SiO₂ 28 nm ZrO₂ 93 nm ZrO₂ 94 nm ZrO₂ 87 nm ITO 6.5 nm ITO 6.5 nm  ITO 6.5 nm  SiO₂ 78 nm SiO₂ 76 nm SiO₂ 77 nm Air Air AirR_(UV) (%) 2.32 (30°) R_(UV) (%) 2.54 (30°) R_(UV) (%) 1.85 (30°) 1.90(45°) 2.00 (45°) 2.53 (45°) h (°) 300 h (°) 300 h (°) 45 C* 12 C* 15 C*7 R_(m) (%) 0.98 R_(m) (%) 1.13 R_(m) (%) 0.87 R_(v) (%) 0.40 R_(v) (%)0.45 R_(v) (%) 0.55 Example 10 Example 11 Example 12 Substrate + hardcoat Substrate + hard coat Substrate + hard coat SiO₂ 150 nm  SiO₂ 150nm  SiO₂ 150 nm  ZrO₂ 14 nm ZrO₂ 14 nm ZrO₂ 14 nm SiO₂ 30 nm SiO₂ 32 nmAl₂O₃ 33 nm ZrO₂ 93 nm ZrO₂ 93 nm ZrO₂ 87 nm ITO 6.5 nm  ITO 6.5 nm  ITO6.5 nm  SiO₂ 75 nm SiO₂ 74 nm SiO₂ 81 nm Air Air Air R_(UV) (%) 0.89(30°) R_(UV) (%) 1.31 (30°) R_(UV) (%) 2.72 (30°) 1.35 (45°) 0.82 (45°)3.22 (45°) h (°) 45 h (°) 45 h (°) 135 C* 7 C* 9 C* 7 R_(m) (%) 0.96R_(m) (%) 1.06 R_(m) (%) 0.61 R_(v) (%) 0.65 R_(v) (%) 0.74 R_(v) (%)0.60 Example 13 Example 14 Example 15 Substrate + hard coat Substrate +hard coat Substrate + hard coat SiO₂ 150 nm  SiO₂ 150 nm  SiO₂ 150 nm Y₂O₃ 39 nm PrTiO₃ 20 nm Y₂O₃ 42 nm Al₂O₃ 16 nm SiO₂ 21 nm SiO₂ 10 nmZrO₂ 85 nm PrTiO₃ 88 nm Y₂O₃ 90 nm ITO 6.5 nm  ITO 6.5 nm  ITO 6.5 nm SiO₂ 81 nm SiO₂ 78 nm SiO₂ 82 nm Air Air Air R_(UV) (%) 3.13 (30°)R_(UV) (%) 2.63 (30°) R_(UV) (%) 2.86 (30°) 3.44 (45°) 3.06 (45°) 3.10(45°) h (°) 135 h (°) 135 h (°) 135 C* 7 C* 7 C* 7 R_(m) (%) 0.61 R_(m)(%) 0.73 R_(m) (%) 0.59 R_(v) (%) 0.60 R_(v) (%) 0.64 R_(v) (%) 0.60Example 16 Example 17 Example 18 Substrate + hard coat Substrate + hardcoat Substrate + hard coat SiO₂ 150 nm  SiO₂ 150 nm  SiO₂ 150 nm  ZrO₂35 nm Al₂O₃ 19 nm ZrO₂ 24 nm SiO₂ 16 nm ZrO₂ 15 nm SiO₂ 27 nm TiO₂ 62 nmSiO₂ 20 nm TiO₂ 9 nm ZrO₂ 23 nm ZrO₂ 91 nm ZrO₂ 69 nm ITO 6.5 nm  ITO6.5 nm  ITO 6.5 nm  SiO₂ 64 nm SiO₂ 82 nm SiO₂ 82 nm Air Air Air R_(UV)(%) 3.87 (30°) R_(UV) (%) 3.15 (30°) R_(UV) (%) 2.23 (30°) 4.71 (45°)3.63 (45°) 2.37 (45°) h (°) 45 h (°) 135 h (°) 135 C* 7 C* 7 C* 7 R_(m)(%) 1.07 R_(m) (%) 0.57 R_(m) (%) 0.62 R_(v) (%) 0.60 R_(v) (%) 0.59R_(v) (%) 0.60 Example 19 Example 20 Example 21 Substrate + hard coatSubstrate + hard coat Substrate + hard coat SiO₂ 150 nm  SiO₂ 150 nm SiO₂ 150 nm  ZrO₂ 26 nm ZrO₂ 40 nm ZrO₂ 33 nm SiO₂ 27 nm SiO₂ 11 nm SiO₂14 nm TiO₂ 10 nm TiO₂ 65 nm TiO₂ 62 nm ZrO₂ 60 nm ZrO₂ 25 nm ZrO₂ 28 nmITO 6.5 nm  ITO 6.5 nm  ITO 6.5 nm  SiO₂ 81 nm SiO₂ 66 nm SiO₂ 72 nm AirAir Air R_(UV) (%) 2.14 (30°) R_(UV) (%) 2.66 (30°) R_(UV) (%) 2.20(30°) 2.63 (45°) 4.27 (45°) 3.66 (45°) h (°) 135 h (°) 135 h (°) 250 C*5.5 C* 6.9 C* 9 R_(m) (%) 0.66 R_(m) (%) 0.80 R_(m) (%) 0.79 R_(v) (%)0.55 R_(v) (%) 0.68 R_(v) (%) 0.48 Example 22 Example 23 Example 24Substrate + hard coat Substrate + hard coat Substrate + hard coat SiO₂150 nm  SiO₂ 150 nm  SiO₂ 150 nm  ZrO₂ 61 nm ZrO₂ 38 nm ZrO₂ 29 nm SiO₂29 nm SiO₂ 14 nm SiO₂ 16 nm TiO₂ 14 nm TiO₂ 70 nm TiO₂ 57 nm ZrO₂ 11 nmZrO₂ 30 nm ZrO₂ 27 nm ITO 6.5 nm  ITO 6.5 nm  ITO 6.5 nm  SiO₂ 72 nmSiO₂ 75 nm SiO₂ 70 nm Air Air Air R_(UV) (%) 2.47 (30°) R_(UV) (%) 1.71(30°) R_(UV) (%) 2.68 (30°) 2.29 (45°) 3.07 (45°) 4.05 (45°) h (°) 250 h(°) 300 h (°) 300 C* 9 C* 15 C* 15 R_(m) (%) 1.05 R_(m) (%) 0.94 R_(m)(%) 1.14 R_(v) (%) 0.59 R_(v) (%) 0.65 R_(v) (%) 0.36 Example 25 Example26 Substrate + hard coat Substrate + hard coat SiO₂ 150 nm  SiO₂ 150 nm Y₂O₃ 62 nm Y₂O₃ 46 nm ZrO₂ 74 nm ZrO₂ 84 nm ITO 6.5 nm  ITO 6.5 nm  SiO₂77 nm SiO₂ 75 nm Air Air R_(UV) (%) 3.79 (30°) R_(UV) (%) 2.97 (30°)3.81 (45°) 2.57 (45°) h (°) 135 h (°) 250 C* 7 C* 8.9 R_(m) (%) 0.92R_(m) (%) 1.07 R_(v) (%) 0.86 R_(v) (%) 0.74

It could be observed that the optical articles of the invention possessvery good antireflective properties in the visible region (Rv<0.86%),with no detrimental influence on the antireflective performances in theultraviolet region (R_(UV)≦4.26% for an angle of incidence of 30° andR_(UV)≦4.71% for an angle of incidence of 45°). The reflection level inthe ultraviolet region of the lenses of the invention remains lower thanthat of a bare ORMA® substrate, for an angle of incidence of 30° or 45°(see Comparative examples hereunder).

Moreover, the lenses obtained in Examples 1 to 26 have outstandingtransparency properties, a good resistance to abrasion and to scratches,and a good resistance to a hot water dip-treatment, followed with amechanical stress on the surface. The adhesion of the coatings to thesubstrate was also very satisfactory.

Another example according to the invention is a ZrO₂ (18.9 nm)/L5substance (22.5 nm)/ZrO₂ (94.7 nm)/(ITO) 6.5 nm)/L5 substance (77.4 nm)stack. (R_(m)=0.77%; R_(v)=0.80%, R_(UV))(45°)=3.5%.

COMPARATIVE EXAMPLES

The antireflective performances on the rear face of four lenses providedwith an antireflective coating, that are quite popular nowadays on themarket, have been determined and are given in the following table:

Comparative examples R_(v) (%) R_(UV) (%) A 0.78 (30°) 26.02 (30°) 19.89(45°) B 0.66 (30°) 10.47 (30°)  8.25 (45°) C 0.39 (30°) 18.15 (30°)15.35 (45°) D 0.56 (30°)  6.58 (30°)  5.51 (45°) ORMA ® bare 3.94 (15°) 4.46 (30°) substrate 4.08 (30°)  5.35 (45°)

It could be observed that the commercially available antireflectivelenses were designed to minimize reflection in the visible region,without being concerned about the reflection in the ultraviolet region,which may reach very high values. Moreover, all the antireflectivecoatings studied did more strongly reflect the UV radiation coming frombehind the wearer (angle of incidence of from 30° to 45°) as compared toa bare lens devoid of any antireflective coating.

1-26. (canceled)
 27. An ophthalmic lens comprising a substrate with afront main face and a rear main face, the rear main face being coatedwith a multilayered antireflective coating comprising a stack of atleast one layer having a refractive index higher than 1.6 and of atleast one layer having a refractive index lower than 1.5 wherein: themean reflection factor on the rear face in the visible region R_(m) islower than or equal to 1.15%; the mean light reflection factor on therear face in the visible region R_(v) is lower than or equal to 1%; themean reflection factor R_(UV) on the rear face between 280 nm and 380nm, weighted by the function W(λ) defined in the ISO 13666:1998standard, is lower than 5%, for an angle of incidence of 30° and for anangle of incidence of 45°; the multilayered antireflective coatingcomprises at least 3 layers; the multilayered antireflective coatingdoes not comprise any layer with a thickness higher than or equal to 20nm based on indium oxide; and the antireflective coating outer layer isa silica-based layer, wherein the antireflective coating comprises, inthe direction moving away from the substrate, a layer having arefractive index higher than 1.6 with a thickness of from 20 to 65 nm, alayer having a refractive index lower than 1.5 with a thickness of from10 to 30 nm, a layer having a refractive index higher than 1.6 with athickness of from 5 to 75 nm, a layer having a refractive index havinghigher than 1.6 with a thickness of from 20 to 75, a layer having arefractive index lower than 1.5 with a thickness of from 60 to 85 nm.28. The lens of claim 27, wherein the multilayered antireflectivecoating does not comprise any MgF₂ layer.
 29. (canceled)
 30. The lens ofclaim 27, wherein the multilayered antireflective coating comprises 7 orfewer layers.
 31. The lens of claim 27, wherein the multilayeredantireflective coating comprises 6 layers
 32. The lens of claim 27,wherein the multilayered antireflective coating comprises 5 or fewerlayers.
 33. The lens according to claim 27, wherein the multilayeredantireflective coating comprises at least one electrically conductivelayer.
 34. The lens according to claim 27, wherein the layer having arefractive index lower than 1.5 is made of silica.
 35. The lensaccording to claim 27, wherein the layer having a refractive indexhigher than 1.6 with a thickness of from 5 to 75 nm is made of zirconia,36. The lens according to claim 27, wherein the layer having arefractive index higher than 1.6 with a thickness of from 20 to 75 nmcomprises titanium.
 37. The lens according to claim 27, wherein theantireflective coating is deposited on a silica-based sub-layer layerhaving a thickness of from 100 to 300 nm.
 38. The lens according toclaim 27, wherein the mean reflection factor Ruv on said rear facebetween 280 nm and 380 nm, weighted by the function W(λ) defined in theISO 13666:1998 standard, is lower than 4.5%, for both an angle ofincidence of 30° and an angle of incidence of 45°.
 39. The lensaccording to claim 27, wherein the mean reflection factor Ruv on saidrear face between 280 nm and 380 nm, weighted by the function W(λ)defined in the ISO 13666:1998 standard, is lower than
 4. %, for both anangle of incidence of 30° and an angle of incidence of 45°.
 40. The lensaccording to claim 1, wherein the mean reflection factor on said rearface in the visible region R_(m) is lower than or equal to 1%,
 41. Thelens according to claim 27, wherein the mean light reflection factor onsaid rear face in the visible region R_(v) is lower than or equal to0.90%,
 42. The lens according to claim 27, wherein the mean lightreflection factor on said rear face in the visible region R_(v) is lowerthan or equal to 0.85%.
 43. The lens according to claim 27, wherein themean reflection factor Rm_uvi on said rear face between 290 nm and 330nm is lower than 15%, for an angle of incidence of 15 [deg.],
 44. Thelens according to claim 27, wherein the mean reflection factor Rm-uv2 onsaid rear face between 300 nm and 320 nm is lower than 4%, %, for bothan angle of incidence of 30° and an angle of incidence of 45°.
 45. Thelens according to claim 27, wherein the mean reflection factor Rm-uv2 onsaid rear face between 300 nm and 320 nm is lower than 3%, for both anangle of incidence of 30° and an angle of incidence of 45°.
 46. The lensaccording to claim 27, wherein the mean reflection factor Rm-uv3 on saidrear face between 300 nm and 380 nm is lower than 5%, for both an angleof incidence of 30° and an angle of incidence of 45°
 47. The lensaccording to claim 27, wherein the mean spectral reflection factor overat least 70% of the 280-290 nm range, for an angle of incidence of 15°is higher than 10%.
 48. The lens according to claim 27, wherein the meanreflection factor over at least 20% of the 280-295 nm wavelength rangeis higher than 5%, for both an angle of incidence of 30° and an angle ofincidence of 45°.
 49. The lens according to claim 27, wherein the meanspectral reflection factor for at least one wavelength in the 280-295 nmrange for both an angle of incidence of 30° and an angle of incidence of45° is higher than 5%.